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Thread: Fill Gap in Button Top with Epoxy?

  1. #1

    Default Fill Gap in Button Top with Epoxy?

    So, I just dented the button top on a Sanyo NCR 18650GA when I dropped my flashlight. I am discarding the dented battery. On my new, non-dented batteries, I'm wondering what would happen if I filled the gap underneath the button top with epoxy? I'm thinking this would stop it from denting but I don't know what affect if any this would have on the battery? Any insights/recommendations would be appreciated. Thanks.

    Also, when I look at the top of the battery using 10x magnification, underneath the button top part, I can see small channels leading to small divot in the center of the top of the battery. I'm not sure why the channels and divot are there? The epoxy would will fill the channels and divot and I have not the slightest clue what harm if any that would cause to the battery.

  2. #2

    Default Re: Fill Gap in Button Top with Epoxy?

    A dented positive end on a GA is fine, it won't hurt its performance or safety. Filling the void with epoxy WILL cause problems because it will prevent the cell from venting if something does go wrong. Those divots are there by design to provide a known failure point.

    ETA: here's a page that goes over these physical safeties https://batterybro.com/blogs/18650-w...-vs-pcb-vs-cid

  3. #3

    Default Re: Fill Gap in Button Top with Epoxy?

    Quote Originally Posted by ferthur View Post
    A dented positive end on a GA is fine, it won't hurt its performance or safety. Filling the void with epoxy WILL cause problems because it will prevent the cell from venting if something does go wrong. Those divots are there by design to provide a known failure point.

    ETA: here's a page that goes over these physical safeties https://batterybro.com/blogs/18650-w...-vs-pcb-vs-cid
    Thanks for this information. I appreciate it.

  4. #4

    Default Re: Fill Gap in Button Top with Epoxy?

    No problem, I hate to see a perfectly serviceable cell go to waste. Plus it would really suck if something did happen and the cell exploded because it wasn't able to vent "safely."

  5. #5

    Default Re: Fill Gap in Button Top with Epoxy?

    Yes, exploding is a serious hazard so that would have been a HUGE mistake on my part.

    I dented the battery on my second use so it seems very wasteful to trash it but, in my case, the dented top causes the battery to rattle.

    I had been using protected cells for the past six years and never had a problem. Two weeks into using these unprotected cells and I already dented my fist battery.

  6. #6

    Default Re: Fill Gap in Button Top with Epoxy?

    How are the button tops attached, as an integral part of the battery or spot-welded onto the positive contact?

  7. #7

    Default Re: Fill Gap in Button Top with Epoxy?

    Integral part. The outside casing of the battery is press fit/molded around the button top.

    I greatly appreciate all of the information on this forum and I'm amazed how some on here modify their flashlights and seemingly know everything. Personally, I would be willing to put on a new shrink wrapper but that's about all I would be comfortable doing.

    I was looking around at other batteries thinking maybe I could find one with a more solid top but I did not succeed at that venture (it must fit inside a SC600w IV Plus). So, I purchased a few back-up batteries and I will just deal with it until Zebralight introduces a new model that addresses this issue or a new battery comes out that is dent proof. To be fair, when reading about this denting issue I saw that it is not exclusive to Zebralight or even flashlights as some people who vape are having the same problem. I do wonder if it's more of a protected cell vs non-protected cell issue.

    I left out a third option which would be to get a different flashlight. For me, at the moment switching flashlights is not an option because I use most of the multiple light output modes on the Zebralight. When I try to find a flashlight that competes with the Zebralight I am not able to do it. I don't like ramping because then I don't know my runtimes. If I could find a high quality flashlight, rated for outdoor use, that has similar UI and form factor to the Zebralight then I would consider it but so far I have not found such a replacement.

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